<iframe id="twitch-chat-embed" src="https://www.twitch.tv/embed/theundergroundlair23/chat?parent=www.theundergroundlair.fr&parent=www-theundergroundlair-fr.filesusr.com" height="500" width="350"></iframe>
is the correct frame
also note I corrected a " on the end of your iframe src (as there was a fault in the HTML), and corrected the parents to match wix’s iframe stack